Elephants Communicate Through Seismic Waves

This African elephant has lifted one foot, placing more weight on the toes of the other foot, to "listen" to seismic signals that can tell much, including danger, the presence of food or water, or the willingness of a potential mate at least two miles away.

Caitlin O'Connell-Rodwell discovered this amazing ability of elephants while working in Africa more than a decade ago, and she recognized it because she had seen similar clues in insects she had studied years earlier at the University of Hawaii.

Today she is a scientist specializing in behavioral ecology at Stanford University, and the research she pioneered now suggests that many animals communicate through subtle shock waves that travel along the earth's surface.

The work lends some scientific credence to the idea that some animals may even be able to predict earthquakes because of weak precursors that arrive before the main shockwave.

That belief has been supported largely by anecdotal evidence, and scientific validation has been hard to come by, but this work suggests that skeptics who scorned the idea may have leaped to a premature judgment.

That, however, remains to be seen, but what is clear at this point is that a number of animals, especially elephants, have some communications skills that eclipse those possessed by humans.

O'Connell-Rodwell was working on a master's thesis on insects called plant hoppers when she documented a peculiar form of communication by a male seeking the attention of a female. The male would freeze, then press down on his legs, go forward a little, then freeze again. No audible signal, but the female got the message.

That set her to wondering if there wasn't a lot more to communications than scientists had thought. It was well known that a number of smaller animals communicated the same way, including some spiders, scorpions, kangaroo rats and golden moles.

But could large mammals also communicate via seismic waves?

Several years later O'Connell-Rodwell was studying in Etosha National Park in northern Namibia when she observed something remarkable.

Elephants Create Vocalizations With High Sound Pressure

"I saw elephants doing the same thing" as the plant hoppers back in the lab, she said in a telephone interview. "I saw elephants paying a lot of attention to the ground, shifting their feet, reorienting them, and then lifting a foot off the ground similar to the way the insects behaved."

Joined by experts from a wide variety of fields, O'Connell-Rodwell and her colleagues have since documented how elephants can communicate over considerable distances, possibly several miles, by seismic waves transmitted through the ground.

The researchers documented much of their research in a recent issue of the journal Physiology, published by the American Physiological Society.

Elephants, of course, are highly vocal but their loud "vocalizations" do more than wake up the neighbors.

Elephants Spread Out Ears to Triangulate Airborne Signals

"The elephant creates this vocalization with such a high sound pressure that it hits the ground, like a mini explosion, so hard that it creates ripples across the surface of the ground," O'Connell-Rodwell said. That's how the elephant sends a message, and other elephants can tell whether the signal is coming from a friend or a foe, and whether danger, or food, is nearby.

The elephant that receives the message also exhibits specific behavior. It also may hear airborne sounds emitted by the sender, so it spreads out its ears to triangulate the signal, thus determining the direction it is coming from.

O'Connell-Rodwell noticed during her many hours of observation that sometimes elephants would freeze simultaneously, even if they were in mid-stride, and press their front feet onto the ground. They might also lift one leg, or roll one foot forward to press the toes against the ground.

The African elephants responded in the same way to signals sent by the researchers, even if the signals were sent only through the ground and there was no audio soundtrack. If the signal indicated danger, the elephants would crowd together in their defensive posture, but only if it sounded like it was from an elephant that lives in the same area.

Elephants Well-Equipped to Communicate Through Seismic Waves

Further study of elephants has shown that they are particularly well equipped to communicate through seismic waves. Their feet, for example, have large fat pads beneath the heel that scientists believe may facilitate transmitting the waves to the elephant's brain. Similar fat pads are found in other mammals, including cats, suggesting that many animals may be using seismic waves to communicate.

An insect may not be able to send a seismic wave very far, but its potential mate may be near. And cats, as many folks know, seem to have an uncanny ability to sense danger.

O'Connell-Rodwell thinks humans may have similar talents, but they probably lie dormant in most of us. Centuries ago, when our ancestors gathered around the camp fire to listen to the village drummer send out both auditory and seismic messages, they may have been a little more attuned to the vibrations in the soil beneath their feet. That could come in handy during a hunt, by the way.

There's some evidence that humans with hearing impairment are also more aware of seismic signals.

"They are much better at detecting vibrations than humans with normal hearing," said O'Connell-Rodwell, who is working in that field as part of her research in Stanford's department of otolaryngology, or head and neck surgery. "Schools for the deaf have wooden dance floors and they play music through the floors and people describe it as hearing the music through their feet."

Can Animals Detect Earthquakes Before They Happen?

I knew a teenage girl years ago who was completely deaf, but could dance as well as anyone on the floor. She knew the music, even if she couldn't hear it.

So if elephants and insects, and some people, can sense seismic signals, is there really anything to those stories we hear about animals detecting an earthquake before it happens?

O'Connell-Rodwell thinks there's probably something to it, but she says the evidence is still woefully lacking.

After the 2004 tsunami disaster struck Southeast Asia there were reports that elephants in Thailand had become agitated and raced to higher ground even before the wave struck the beaches. They may have sensed minor precursor shock waves before the major shock hit the area, but maybe not.

O'Connell-Rodwell points out that a group of elephants in a national park in Sri Lanka had been equipped with satellite collars, and they didn't move at all before the tsunami struck. But seismic waves behave differently in different soils, so it's possible the precursors could be detected in Thailand, but not Sri Lanka.

Although some experiments in Japan and China suggest that some animals, even catfish, can predict earthquakes, the record remains incomplete. All of this suggests, O'Connell-Rodwell said, that there's still much to be learned about communications among animals that humans tend to think are a tad dumb.